Preterm birth (PTB) is the most common complication of pregnancy, with over 500,000 early births annually in the United States. PTB is responsible for the majority of neonatal deaths and newborn illnesses. Unfortunately, the ability to assess PTB risk prior to contractions is not available clinically; this capability would enable therapeutic interventions that prevent or forestall delivery, potentially decreasing PTBs and/or the severity of neonatal complications. This renewal proposal focuses on the development of an integrated microfluidic platform for rapid, sensitive and inexpensive quantitation of serum PTB risk biomarkers (newly discovered peptides and known proteins), weeks before contractions occur. This proposal thus offers a major human health impact, potentially decreasing the prevalence of PTBs and their associated complications. This proposal tests the hypothesis that further development of microfluidic systems, which combine sample preparation, separation and quantitation in a single platform, will enable the direct measurement of PTB biomarkers in serum, allowing risk assessment and preventative measures to occur well before contractions begin. The proposed automated microfluidic platform has three main components: (1) a multiplexed immunoaffinity extraction module to selectively capture unlabeled PTB biomarkers; (2) a purification/labeling module to enrich PTB biomarkers and then allow fluorescence labeling with removal of unreacted tag; and (3) a microchip electrophoresis module to separate the labeled PTB biomarkers, enabling their quantitation. This approach improves significantly over present instrument- and personnel-intensive methods to determine PTB biomarkers, and should offer specificity comparable to sandwich immunoassays that would be problematic to develop for small peptide targets. The goal of this renewal proposal is to further develop integrated microfluidic systems for convenient, inexpensive, rapid and quantitative analysis of serum biomarkers with PTB risk correlation. This objective will be accomplished via three specific aims. In Aim 1 electrokinetically operated microchips to quantify PTB biomarkers will be created and tested, integrating immunoaffinity extraction, solid-phase enrichment, fluorescence labeling, electrophoretic separation and biomarker quantitation. Aim 2 will involve developing PTB biomarker analysis microdevices that use pressure actuation of on-chip valves and pumps to carry out integrated sample preparation operations. Performance of the devices from Aims 1 and 2 will then be compared. In Aim 3 these microfluidic platforms will be used to measure PTB biomarkers in blood samples to establish the feasibility of microchip methods in predicting PTB risk weeks before contractions occur. Importantly, this work addresses the urgent need to diagnose PTB risk when therapeutic intervention is still feasible; however, the general nature of the approach should be applicable well beyond biomarkers for PTB, further exemplifying the large and important health impact of these studies.